1. Field of the Invention
The invention relates to portable alarms and, more particularly, to an exceedingly compact, lightweight alarm especially adapted for use as a medical alert alarm.
2. Description of the Prior Art
Portable alarms per se have been known for some time. Generally speaking, these alarms consist of a battery powered speaker housed in a casing having an external switch. By activating the alarm in the event of imminent or suspected illness, an individual can alert bystanders to the fact of a medical problem and help can be summoned. Other portable devices of this nature are known in which a small radio transmitter carried by the individual can be activated. The signal thus transmitted, upon being received by an appropriate facility such as a hospital or rescue squad, can serve as notice to summon help.
A problem with prior alarm devices relates to their bulkiness. Obviously, the devices must be small enough and light enough to be carried conveniently by individuals. The smallest known medical alert alarms previously available have been about the size of a pack of cigarettes (approximately 21/2".times.31/2".times.1"). Although the size of the smallest medical alert alarm is considerably smaller than early medical alert alarms, further improvements in size reduction are desired. It is expected that a smaller medical alert alarm not only would be more convenient to carry, thereby encouraging more people to use such alarms, but a smaller alarm should be less expensive because of the need for fewer materials.
A problem with reducing the size of medical alert alarms relates to the audible signal which must be produced. Known medical alert alarms associated with cardiovascular medicine emit a distinctive signal having a frequency of approximately 640 Hertz. The signal produced by prior devices purposefully is quite shrill, and immediately attracts attention to itself and indicates to those nearby that a cardiac standstill has occurred. Unfortunately, devices capable of producing a signal having the proper attention-getting characteristics have been rather bulky. It is believed that prior medical alert alarms have not been smaller because of the size of the components needed to produce a proper medical alert signal.
In view of the foregoing considerations, it is an object of the present invention to provide a medical alert alarm which is exceedingly compact and lightweight.
It is an additional object of the invention to provide a medical alert alarm having audio oscillator circuitry and a resonant cavity adapted to produce a signal having desired medical alert characteristics.